Two way communication using light links

ABSTRACT

Two-way communications between a video system and a control device is disclosed. The communications links comprise visible light, IR light, or a combination of visible and IR light. The communications link provide a convenient route to capture data or lock system features or various combinations thereof.

FIELD OF THE INVENTION

The present invention relates to hand-held remote control modules, aswell as consumer electronic devices. Specific exemplary embodimentsdiscussed relate to hand-held remote controls and televisions connectedto cable set-top boxes.

BACKGROUND OF THE INVENTION

The description of art in this section is not intended to constitute anadmission that any patent, publication or other information referred toherein is “prior art” with respect to this invention, unlessspecifically designated as such.

While the present invention relates to hand-held control modulesgenerally, it will be better understood within the discussion ofexemplary embodiments directed toward universal remote controls.Universal remote controls typically offer a preprogrammed set ofstandardized keys for each device type supported. These provide for thecommon operational functions of the device but do not necessarily offerthe full range of features available on the original manufacturer'sremote.

U.S. patents and applications relevant to remote control technologyinclude U.S. Pat. Nos. 5,515,052; 5,255,313; and U.S. patent applicationSer. No. 09/418,091 filed Oct. 14, 1999, which are incorporated hereinby reference. Pat. '052 discloses a universal remote control withfunction synthesis. The remote control comprises driver circuitry forcommunicating code signal generation sequences including a codegenerated command signal followed by a code setting signal; and memoryfor storing information therein. Pat. '313 discloses a universal remotecontrol system having a signal generator to transmit signals which willcause specific functions to occur in specific controlled devices. Patentapplication Ser. No. '091 discloses means and methods for operating aremote control.

Users of universal remote controls who need access to one or morefunctions not 5 preprogrammed into the unit must then use a learningcapability or a feature, such as a function synthesizer (e.g., thefunction synthesizer discussed in Pat. '052) to add the desired extrafunctions to their remotes. Other U.S. Patents related to remote controltechnology, and in particular, relating to learning technology includeU.S. Pat. Nos. 4,959,810, 5,228,077, and 5,537,463 which areincorporated herein by reference.

Pat. '810 discloses means for transferring instructions and/or data toRAM wherein the instructions and/or data is transferred from a sourceexternal to the RAM.

Pat. '077 discloses a remotely upgradable universal remote control. Pat.'463 discloses means in the remote control for picking up anelectromagnetic signal from an electro-magnetic signal source andstoring output signal data in memory. The output signal data stored inmemory may correspond to control function data which may be transmittedto a device to be controlled.

U.S. Pat. No. 5,481,256, issued Jan. 2, 1996, is incorporated herein byreference. The '256 patent discloses circuitry for coupling a SCAN keyto a microprocessor and a channel scan program. A channel scan ofchannels is initiated when the SCAN key is depressed.

U.S. Pat. No. 5,414,426, issued May 9, 1995, is incorporated herein byreference. The '426 patent discloses an entry program for enabling auser to define a macro for selecting at least one favorite channel,whereby rapid selection of at least one favorite channel is made uponsubsequent depression of a MACRO key.

A drawback of the prior art is that programming a remote control, forexample to create a favorite channel list, can be tedious. Accordingly,it would be useful if there were a “short cut” way to indicate to theremote control that the channel currently being viewed should be addedto the list. This would allow the user to build a favorite channel listby simply pressing a key, labeled for example “Thumbs Up”, whenever theuser came across a channel he liked. Likewise, a “Thumbs Down” key couldbe used to delete a channel that fell out of favor.

A challenge in implementing this feature is that the remote controlgenerally is not able to precisely track which channel number iscurrently being viewed. On many TV sets, for example, action of the CH+and CH− keys does not necessarily advance channel numbers in exactnumerical order. Also, the effect of holding one of these keys for alonger period is not predictable.

The tuning device (cable or satellite STB, TV set, etc.) does howeveralways know the current channel number. So if a low cost method could bedevised to transmit this information back to the remote control on thereceipt of a “Thumbs Up” key press, such a feature could be implementedin the remote control.

Transmission of data together with television signals are known andinclude, for example: Vertical Blanking Interval (VBI), e.g., Teletextand Closed Captioning, FM broadcast radio sub-carrier, and cellulartelephone-like data systems. Such systems have been complex and notreadily available to most TV viewers.

U.S. Pat. No. 5,594,493, which issued Jan. 14, 1997, and is incorporatedherein by reference, discloses transmitting data information along withany standard TV video signal for reception by a “smart card” held nearthe screen. The smart card includes circuitry, a LCD display screen anda plurality of buttons for interacting with the user. The '493 systemutilizes a signal with the data imbedded in the video signal. Thus,video and data signals are received simultaneously and with equalclarity. The '493 patent teaches sending data transmission along with astandard television signal in the form of changing light pulses; thedata signal is invisible to the user. The light modulation is thensensed by a photoelectric pickup device within the smart card where itis captured and stored. The data can then be displayed and read at aterminal at a redemption center, for example.

U.S. Pat. No. 5,410,326, which issued Apr. 25, 1995, and is incorporatedherein by reference, discloses a universal remote control having a touchscreen, capable of displaying icons, and a opto-photo signal detector.When advertising indicia is imbedded in a video signal being displayedon a television receiver, the opto-photo signal detector will detect theencoded video signal and supply a digital data stream to an analogsignature and signal processor. The variations in luminance are decodedto provide the corresponding serial data stream to the microprocessor.

Both the '493 and '326 patents comprise overlaying or merging the datastream with the video signal. Also, the data stream is always on—theremote “looks up” and receives the data stream via light transmissions.The video system does not respond to queries from the remote control to,for example, provide its current state.

The following U.S. patent applications disclose methods for controllingmedia systems and for capturing state information. U.S. patent Ser. No.09/718,931, filed Nov. 21, 2000, and U.S. patent Ser. No. 09/418,091,filed Oct. 14, 1999, are incorporated herein by reference. The '931application discloses a media return system with return to statecapability. The status of the system is quickly captured and provides asimple means to reset the system to, for example, the state prior tochannel surfing. The '091 application discloses a media system withpunch-through capability. Functional control may be locked acrossdevices to control a particular device while operating in a differentdevice mode.

This document teaches two-way communication methods differing from thosedisclosed in the '326 and '493 patents. Particular embodimentscomplement the various media systems and methods disclosed in the '931and '091 patent applications.

SUMMARY OF THE INVENTION

This document describes a method for a two-way communications linkbetween a set-top box hooked up to a television or the like (hereafterreferred to as “video system”), which can transmit information back to aremote control (also referred to as “receiver”). This facilitatestransmitting the current setting of the video system to the remotecontrol using existing hardware (with added software) on the videosystem side.

Infrared (IR) is used by the remote control to communicate/control thevideo system and visible light is used by the video system tocommunicate its status to the remote control.

This system will facilitate the design of user friendly remote controlunits, which can be programmed to gather user preferences/settings fromthe video system and use this information for a variety of controlscenarios, enhancing the functionality of the remote control.

An object is to provide a method of communicating information to aremote control using existing hardware in set top boxes.

Another object is to provide a method for imparting status informationof a particular media parameter to a controlling device. A specificapplication is directed toward indicating the current channel to theremote control.

Other objects and advantages will be apparent to those of skill in theart from the teachings disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

In the interest of enabling one of skill in the art to practice theinvention, exemplary embodiments are shown and described. For clarity,details apparent to those of skill in the art and reproducible withoutundue experimentation are generally omitted from the drawings anddescription.

FIG. 1 depicts a block diagram of a media system and process forrequesting information from the video system.

FIG. 2 depicts a flow chart diagram of an exemplary method fortransmitting data from the video system.

FIG. 3 depicts a flow chart diagram of an exemplary method for receivingdata from the video system.

FIG. 4 depicts a schematic diagram of an exemplary system for producinga signal. For clarity, the video switch and IR receiver are not shown.

FIG. 5 depicts a schematic diagram of an exemplary system fortransforming the received optical signal to an electrical signal thatcan be interfaced to a microprocessor.

FIG. 6 depicts a flow chart diagram of an exemplary method for modifyinga favorite channel scan table.

FIG. 7 depicts a flow chart diagram of an exemplary method for insertinga channel into a channel scan table.

FIG. 8 depicts a representative channel scan table.

FIG. 9 depicts a flow chart diagram of an exemplary method for removinga channel from a channel scan table.

FIG. 10 depicts a logic flow diagram for interrogating a set top box(STB) within the system.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

This disclosure is discussed in relation to remote controls, however,other uses will be apparent from the teachings disclosed herein. It willbe better understood from the following detailed description ofexemplary embodiments with reference to the attached drawings, whereinlike reference numerals and characters refer to like parts, and byreference to the following claims.

FIG. 1 depicts a typical modern video system 10. The video systemcomprises a video monitor (display or monitor) 12 that is typically atelevision and a set top box 14 for receiving an encrypted signal andproviding a video signal to the video monitor. A remote control 16typically controls channel selection and other parameters of the system.

Most modern video systems already have the facility to produce coloredscreens. Typically this facility is used to blank out a picture (e.g.,display a blue screen) during the absence of a video signal.

The video system's screen 18 can be flashed in order to transmit itsstatus. A bright screen could be considered a digital ‘1’ and a darkscreen could be considered a digital ‘0’. In this way a serial datastream can be produced at a low baud rate, organized into ASCIIcharacters for the transmission of text like information.

A receiver in the remote control 16 preferably comprises a circuitoptimized to receive flashing visible light, and thereby receive serialinformation. The remote control 16 also comprises a microprocessor orcircuit capable of decoding the serial information and processing it.

In such a system, the steps for conveying information to the remotecontrol may comprise:

1. Request information 20 from the video system 10 using an infraredremote control 16 (The requested information, in a preferred embodiment,is the identification of the current channel);

2. The video system processes the request 20 and transmits the answer 22in a signal; and

3. The remote control 16 receives the signal 22 and decodes it.

For added reliability a fourth step can be added in which the remotecontrol 16 can re-transmit the received information to the video system10. In response, the video system 10 can transmit an OK signal (i.e.,the remote control 16 received the correct information) or a BAD signal(i.e., the remote control 16 did not receive/process/etc. the correctinformation) to the remote control 16.

The above method is an exemplary method for implementing two waycommunications using existing hardware on the video system 10. Themethod preferably uses existing well defined serial protocol. Suchmethods allow the current state of video system 10 to be shared withother devices not physically attached to it.

FIG. 2 is a block diagram of a transmitter 30 which may be used to causethe video monitor 18 to flash in response to a request 20. For claritythis transmitter 30 is shown separate from and connected to the set topbox 14 via a serial port 32. It will be appreciated however that mostset top boxes already include a screen generator 34 for generating, forexample, black and white screens, a controller 36, such as amicroprocessor, an IR input port 38 for receiving control commands from,for example, a remote control 16, and video switching capability(provided via, for example, video switch 40) to switch the output signal46 between a video-in signal 42 and a (light-dark) screen generatorsignal 44. Since the transmitter 30 components are typically withinexisting set top boxes as described above, in many cases the appropriatesoftware can be downloaded to the set top box by any number ofconventional processes and no additional hardware is required.

A receiving section 50 of a remote control 52 compatible with theteachings in this document is shown in FIG. 3. The receiving section 50comprises an optical receiver 54 for receiving visible light and acontroller 56 for decoding the light received. The conventionalfunctions of the remote control are indicated by block 58.

The diagrams of FIGS. 2 and 3 are only examples. Each block can beimplemented as a stand-alone function or within other functional blocks.In particular, most or all of the functions shown in FIG. 2 may beimplemented within the set top box 14 if so desired. The figures arediscussed in more detail below:

FIG. 2 illustrates in functional block form, elements for transmittingdata from the video system 10 using the method described below. Othermethods are also acceptable. The steps conforming to FIG. 2 comprise:

1. A request to transmit data is input via the IR receiver;

2. The system processes this request and develops a response;

3. The existing video signal is interrupted using a switching means andis connected to a screen generator; and

4. The generator flashes the screen in accordance with thepre-established serial protocol and baud rate effectively transmittingthe response using visible light (e.g., White=Logical ‘1’ andBlack=Logical ‘0’).

FIG. 3 illustrates in functional block form elements for receiving datafrom the video system 10 using the method described below. Other methodsare acceptable.

In addition to the existing infrared transmitter, e.g. the basic remotecontrol 58, an optical, visual light, receiver 54 is utilized which cantransform the light signal to electrical signals. These signals are thensent to a microprocessor 56 for decoding. The microprocessor 56 could bethe existing processor in the remote control or an additional one thatis linked to the remote control's processor.

The transmitter 30 of the information to the remote control 16 performsthe functions as outlined in FIG. 2. A microprocessor 36 fromMicrochip's PIC family was chosen because it is inexpensive and has thespeed to perform signal generation. Example algorithms for using thisprocessor to implement serial communications and black-and-white videosignal generation are readily available on the Internet and from othersources. It will however be appreciated that other equally suitablemicroprocessors are also available. In order to generate an NTSCcompatible signal a minimum of three discrete voltage states areutilized. With a simple microprocessor algorithm up to four states canbe accomplished using a voltage divider attached to two microprocessorI/O ports by selectively connecting either port to system power orground. With accurate timing from a crystal controlled microprocessorclock oscillator, a simple NTSC black and white signal can thus begenerated. A detailed exposition of one such software algorithm may befound, for example, at http://www.efd.lth.se/˜e96rg/mc/video/rtvideo.htmand, for the sake of brevity, no further description will be providedherein.

FIG. 4 is an exemplary schematic of a circuit to implement the controland signal generation portions (34,36,44) of the transmitter 30 shown inFIG. 2. The video switch 40 and IR receiver 38 are not included forclarity. Both the IR receiver 38 and video switch 40 are connected viaJP1, while serial communication 32 to the set top box 14 is via J1. JP2is used if needed to set user preferences on start up (for example, PALversus NTSC video signaling). Resistors R1 and R2 connected tomicroprocessor U1's I/O ports RA0 and RA1, in conjunction with the75-ohm impedance of the video output cable connected to P1, form thevoltage divider described above.

FIG. 5 illustrates an exemplary circuit 60 for use in the receiver 52 totransform the received optical signal 22 to an electrical signal whichcan be interfaced to a processor. This is by no means the only way to dothis. There are four stages in circuit 60 shown in FIG. 5. They are:

1. CdS Cell/Voltage Divider 65;

2. Amplifier 66;

3. Comparator with hysteresis 67; and

4. One shot 68.

CdS Cell/Voltage Divider

Since the receiver 52 will typically be some distance from thetransmitter 30, a means to concentrate the optical signal 22 onto thetransducer is preferred. The optical signal 22 can thus be focused onthe CdS (Cadmium Sulfide) transducer cell 62 using a lens and light pipe64 to minimize interference from stray light. The CdS cell changesresistance as light strikes it and forms one leg of a voltage dividercircuit. As light hits the cell 62, its resistance changes and the ratioof the divider is changed causing a voltage shift at the junction of thedivider. Since the signal coming from the video source is transitorythis signal is AC coupled 61 to the amplification stage.

Amplifier

This stage and the comparator stage get their references from the samesource as the divider (Vcc or power supply). This makes the entirecircuit ratiometric and less susceptible to power supply variation. Theamplifier 66 is configured to be an AC amplifier whose DC output is ½Vcc. The AC gain can be set by varying the ratio of Rf to Ri as shown inFIG. 5. The signal is next coupled to a comparator.

Comparator With Hysteresis

The comparator 67 compares the signal from the amplifier against a knownreference and produces a logical ‘1’ or ‘0’. For reliability, some smallamount of positive feedback should be incorporated to snap the outputsignal and keep it from oscillating at the transition point.

One Shot

The signal is then fed to a one shot timer 68 to process out any 50 or60 Hz scanning artifacts in the signal that may be present in someCathode Ray Tube (CRT) monitor screens (item 18). The one shot featurecould be implemented either in hardware as shown or in software usingthe remote control's microprocessor. Following this stage, the signal issent to the microprocessor for processing as described below.

FIG. 6 is a logic flow diagram 70 for modifying a channel scan table. Inresponse to a key selection, the remote control 16 determines if the keyselected is the “add-a-channel” key or the “remove-a-channel” key. Steps72-74. The “add-a-channel” and “remove-a-channel” keys are respectivelyrepresented by thumbs-up and thumbs-down icons. If the key selected isnot a channel table modification key, the functions associated with theselected key are performed in a normal manner. Step 76. If the user hasindicated a desire to modify the channel table (by selecting one of thethumbs-up/down icons), the remote control 16 will interrogate the STBvia IR channel request 20 as illustrated in FIG. 10. Step 78. If thedata received from the STB is good, then the identified channel will beadded, in accordance with FIG. 7, or deleted, in accordance with FIG. 9,depending on which thumbs-up/down icon was selected. Steps 80-86. If thedata is bad, the remote control will request the channel identificationagain, for a predetermined number of time. Steps 80 and 88-90.

FIG. 7 is a logic flow diagram 100 for inserting a channel into the scantable 102 depicted in FIG. 8. If the table has not reached its maximumlimit, the channel identifier is stored in the table and the LIMITcounter is advanced by one. Steps 104-110. If the table is full, theuser will be notified, for example by an error message or flashinglights, that the table is full and the new channel cannot be added. Step112.

FIG. 9 is a logic flow diagram 120 for deleting a channel from scantable 102. The table pointer TABLE_PTR is moved through the table 102,typically stepwise, until the value stored in the table is equal to thevalue of the channel identified by the STB 14 via optical signal 22.Steps 122-130. The table limit, i.e., the number of channels in thetable, should be reduced. If the channel to be deleted is located at thetable limit, then reducing the table limit at that point has the effectof removing the channel-to-be-removed from the table. Steps 132-134. Ifthe channel-to-be-removed is not at the table limit, then the values ofeach successive cell is copied into each preceding cell. In effect thechannels above the channel-to-be-removed each take a step down in thetable, thereby pushing the channel-to-be-removed out of the table andreducing the limit of the table. Steps 134-138.

For more details on modifying a scan table, refer to U.S. Pat. No.5,481,256 issued Jan. 2, 1996, which is incorporated herein byreference.

FIG. 10 shows logic flow diagrams 140 and 170 for interrogating STB 14and transmitting channel data (via optical signal 22) to remote control16. The remote control 16 sends IR channel request 20 to STB 14, enablesthe optical receiver 50 and then waits a predetermined time to receiveand decode 16 bits of channel identification data. Steps 142-160. If 16bits of data are not received within the predetermined time interval,the receiver logic 140 sets a “Bad Data” status flag (for use at step80, FIG. 6) and then exits after shutting down the optical receiver.Steps 150 and 152.

After the STB 14 receives channel request 20, it sends, in binary serialform via optical signal 22, the channel identification data. Then achecksum is sent. Steps 172-178. After the data has been received by theremote 16, a checksum validity test is performed to determine if thedata received is valid and a status flag set accordingly (for processingat step 80, FIG. 2) and the optical receiver is shut down. Steps180-186.

While aspects of the invention has been particularly shown and describedwith reference to particular embodiments thereof, it will be understoodby those skilled in the art that various changes in form and detail maybe made therein without departing from the spirit and scope of theinvention. The scope of the claimed invention is intended to be definedby following claims as they would be understood by one of ordinary skillin the art with appropriate reference to the specification, includingthe drawings, as warranted.

1. A media system comprising: a video screen; a screen generatorconnected to the video screen and comprising programming to flash thevideo screen to convey via a predetermined serial protocol channelidentification information that functions to specify a channel that iscurrently being displayed on the video screen; and a remote controlcomprising: a memory having a favorite channel table; an opticalreceiver connected to receive the video screen flashes and convert themto an electrical signal; a controller connected to the optical receiverfor decoding the electrical signal to thereby store in the favoritechannel table of the memory the channel identification information; andprogramming response to actuation of a favorite channel key whichretrieves from the favorite channel table of the memory the channelidentification information and which uses the channel identificationinformation to cause a transmission of a command adapted to tune anappliance to the a channel corresponding to the channel identificationinformation.
 2. The media system of claim 1, wherein the video screen isoperably connected to flash light and dark screens.
 3. (canceled) 4.(canceled)
 5. A method of editing a favorite channel table in a remotecontrol, the method comprising: transmitting from the remote control toa video system a channel identification request; receiving through anoptical receiver in the remote control a series of video screen flashes;decoding the series of video screen flashes to determine the channelidentification; and modifying the favorite channel table in the remotecontrol with the channel identification; wherein the channelidentification functions to specify a channel that was being displayedon a video screen when the channel identification request wastransmitted.
 6. The method of claim 5, wherein modifying the favoritechannel table comprises deleting from the favorite channel table achannel corresponding to the channel identification.
 7. The method ofclaim 5, wherein modifying the favorite channel table comprises addingto the favorite channel table a channel corresponding to the channelidentification.
 8. A computer readable medium for use in a remotecontrol, the medium comprising programming for: transmitting via IR achannel request to a video system; receiving by an optical receiver inthe remote control a series of video screen flashes transmitted by thevideo system, the video screen flashes functioning to specify a channelthat was being tuned to by the video system when the channel request wastransmitted: determining the a channel based upon the series of videoscreen flashes transmitted by the video system and received by theoptical receiver in the remote control; and modifying a favorite channeltable stored in memory of the remote control with the determinedchannel.
 9. The medium of claim 8, comprising programming for: sensing auser activating a predetermined key input on the remote control;initiating the transmission of the channel request in response tosensing the predetermined key input; and basing the programming formodifying the favorite channel table on the predetermined key input. 10.The medium of claim 9, wherein the predetermined key input consists of asingle key input.
 11. The medium of claim 10, wherein the programmingfor modifying the favorite channel table comprises programming foradding to the table a channel corresponding to the determined channel.12. For use in a remote control having a memory, a method for storingand using channel identification information, comprising: receiving asignal that functions to specify a channel that is currently being tunedto by an appliance; converting the signal to an electrical signal;decoding the electrical signal to obtain the channel identificationinformation; storing the channel identification information in afavorite channel table of the memory; and in response to actuation of afavorite channel key, retrieving from the favorite channel table of thememory the channel identification information and using the channelidentification information to cause a transmission of a command adaptedto tune an appliance to a channel corresponding to the channelidentification information.
 13. The method of claim 12, comprisingtransmitting a request to receive the signal.
 14. The method of claim12, wherein the signal comprises a visible light pattern flashed on avideo display.
 15. The method of claim 12, wherein the signal comprisesa serial transmission of data.
 16. For use in a remote control having amemory, a computer-readable medium having instructions for storing andusing channel identification information, the instructions performingsteps comprising: converting a received signal to an electrical signalthe received signal functioning to specify a channel currently beingtuned to by an appliance; decoding the electrical signal to obtain thechannel identification information; storing the channel identificationinformation in a favorite channel table of the memory; and in responseto actuation of a favorite channel key, retrieving from the favoritechannel table of the memory the channel identification information andusing the channel identification information to cause a transmission ofa command adapted to tune an appliance to a channel corresponding to thechannel identification information.
 17. The readable medium of claim 16,wherein the instructions perform the step of transmitting a request toreceive the signal.
 18. The readable medium of claim 16, wherein thesignal comprises a visible light pattern flashed on a video display. 19.The readable medium of claim 16, wherein the signal comprises a serialtransmission of data.